The "data" in any manual is ONLY a guide, as all components differ, as do guns.

Never start your loading at MAX; as your manual teaches you start low and work up slow. There is no "cushion" built in whatsoever, as your gun's MAX may be significantly lower (or higher) than the data suggests.

Manuals do not offer recipes, they offer information to help you develop load data for your components and gun.

That can't be right, since the Hornady Manual 8th edition is copyrighted 2010.

So, no telling what manual the OP is really asking about.

As for ACTUAL Hornady manuals, they use a somewhat different format than most, which I find more useful. They publish a table for each bullet in a particular cartridge, with the powders listed down the left side and the velocities listed along the top in increments of 50 or 100 fps, depending on the cartridge. The table entries are the charge weights of the powders that give the various listed velocities. Where the charge weight of a particular powder needed for a particular velocity is over SAAMI pressure spec, the entry is left blank. Likewise, when the load for a particular velocity is so low in pressure that it might create erratic burning or leave a bullet stuck in a barrel, the table entry is left blank.

So, the Hornady table typically showes a substantial range of useable charge weight for each powder rather than just the max and a "start" value that is 10% less than max (or, perhaps just 3% less for some powders like W-296).

In the Hornady format, the largest charge weight for a particular powder in a table might not be the weight that gives the SAAMI pressure limit, because the charge weight that produces that limiting pressure would not get the velocity up to the next velocity increment shown by the table. So, in that sense, the Hornady max loads might not be "absolutely max". But, they are typically close enough to max that it isn't going to give you any significant benefit to exceed them.

I'll be honest. Without a good chronograph to tell you if/when you are over-driving the expected
velocity, you will never know until primers leak/crater/puncture and/or primer pockets loosen up.

Even then, different barrel lengths/chambers/temperatures.brass volumes will have to be accounted
for in comparing expected vs actual velocties, which is where an internal ballistics program like
QuickLoad comes into play.

Are the max loads listed in a manual "safe"?

After you see the disparity between what different manuals and on-line powder manufacturers
list as their Max loads, you will better appreciate the the expression "YMMV"

CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.

Quote:

rebs I have the Hornady 45th edition book, is it safe to reload the factory duplicate loads ?
When they state maximun load, is there a cushion built in there, is it safe to load a max load ?

Razor thin margins:
The cushion is as small as they can make it with 270Win, 6mmRem, and 22-250 Rem. At 65 kpsi SAAMI registered max average 84.5 kpsi - 91 kpsi proof loads, the case head of these cartridges is on the edge. They use the 1889 7.65x53mm case head, and when built with a large Boxer primer pocket, it is possible for me to load at 67 kpsi for one rifle and have enough safety margin to allow for variations in components, my reloading process, and temperature.

Bigger margins:
The 260 Rem was registered with SAAMI at 62kpsi.
I can't help but think the thin margins of the 270, 6mm, and 22-250 were making problems with factor ammo in factory rifles.
I load it at 67 kpsi, for obvious reasons.

Even bigger margins:
The .223 Rem is registered at 55 kpsi, and I load it at 75kpsi and get long brass life.

Even bigger margins:
If someone gives me a another 25acp that I have never seen that make or model before, if I see it is made of thick steel, good firing pin to firing pin hole fit, and good case support, then I will start the work up at double max book loads, and probably end with my maximum usable load somewhere around 2.5 times the maximum published book load.

What does it all mean?
There are tiny margins [cushion] in guns and cartridges and then there are huge margins, but where they are is a secret.
If the information got into the hands of ordinary consumers, they might hurt themselves.
And there is big money in overloading a cartridge and giving a new name.
To find out where the margins are exploitable, you must know the secret handshake, to design new guns and new cartridges.
That is what I am doing today, designing and building gun parts for a wildcat.

__________________
The word 'forum" does not mean "not criticizing books."
"Ad hominem fallacy" is not the same as point by point criticism of books. If you bought the book, and believe it all, it may FEEL like an ad hominem attack, but you might strive to accept other points of view may exist.
Are we a nation of competing ideas, or a nation of forced conformity of thought?

__________________
Still happily answering to the call-sign Peetza.
---
The problem, as you so eloquently put it, is choice.
-The Architect
-----
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.

Brian,
That link has multiple posts by me [alias tnekkc] and Denton Bramwell.
We are two old electrical engineers as different as the two old Greek philosophers, Plato and Aristotle.
Just as Aristotle did not agree with Plato's Allegory of the cave, taking leave of one's senses and not trusting one's senses, I do not agree with Denton's ignoring the observations on the weak link, brass, and instead pursuing the abstract notion of measuring pressure with strain gauges and comparing to SAAMI registered values.

__________________
The word 'forum" does not mean "not criticizing books."
"Ad hominem fallacy" is not the same as point by point criticism of books. If you bought the book, and believe it all, it may FEEL like an ad hominem attack, but you might strive to accept other points of view may exist.
Are we a nation of competing ideas, or a nation of forced conformity of thought?

The .223 Rem is registered at 55 kpsi, and I load it at 75kpsi and get long brass life.
are you loading this in an AR 15 or what ?

This is a piece of 223 brass fired in one of my AR15s.
Notice the extractor and ejector marks on the brass?
There are these problems, plus the AR15 is not adjustable for variations in barrel gas pressure - time.

Here is a work up from 66 kpsi to 99kpsi in 223 in a Ruger #1.
Notice how much more supportive the breach face is in the #1?

__________________
The word 'forum" does not mean "not criticizing books."
"Ad hominem fallacy" is not the same as point by point criticism of books. If you bought the book, and believe it all, it may FEEL like an ad hominem attack, but you might strive to accept other points of view may exist.
Are we a nation of competing ideas, or a nation of forced conformity of thought?

My primers look about the same as they do when I shoot factory federal rounds. So maybe they are normal. The primer is kind of flattened out, looks like against the bolt face. There are no extractor or ejector marks on them and none of the other signs of over pressure.

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